A typical corrugator includes one or more pairs of operating-ring-supporting members in the form of rods or bars to support a number of operating rings which have edges to fold, score, slit, crease or otherwise operate on sheet products, such as, for instance, corrugated carton paper, whereby to provide carton forms which can be folded and interfitted to form cartons of corrugated paper. In prior machines of which I am aware, an operating ring has comprised a pair of halves which are secured together at their ends by bolts or screws. When it becomes necessary to adjust the positions of the rings longitudinally on their support members, the grip of each operating ring on its support member must be individually and separately relaxed by backing off one or more of the associated bolts or screws, the new position established, whereafter the grip of the operating ring must then be individually and separately reestablished by tightening the bolts or screws. This one-at-a-time operation is time-consuming and causes longer shut down time of the corrugator than is desired.